e1000e: PHY loopback broken on 82578

PHY loopback on 82578 fails to work as a result of flushing the packets
in the FIFO buffer in the link stall workaround.  Don't perform the
workaround if in PHY loopback mode.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 7 insertions, 0 deletions

diff --git a/drivers/net/e1000e/defines.h b/drivers/net/e1000e/defines.h
index 8890c97e1120..4329ec34b178 100644
--- a/drivers/net/e1000e/defines.h
+++ b/drivers/net/e1000e/defines.h
@@ -575,6 +575,8 @@
 #define PHY_1000T_STATUS 0x0A /* 1000Base-T Status Reg */
 #define PHY_EXT_STATUS   0x0F /* Extended Status Reg */
 
+#define PHY_CONTROL_LB   0x4000 /* PHY Loopback bit */
+
 /* NVM Control */
 #define E1000_EECD_SK        0x00000001 /* NVM Clock */
 #define E1000_EECD_CS        0x00000002 /* NVM Chip Select */
diff --git a/drivers/net/e1000e/phy.c b/drivers/net/e1000e/phy.c
index e23459cf3d0e..d8453946bff8 100644
--- a/drivers/net/e1000e/phy.c
+++ b/drivers/net/e1000e/phy.c
@@ -2737,6 +2737,11 @@ s32 e1000_link_stall_workaround_hv(struct e1000_hw *hw)
         if (hw->phy.type != e1000_phy_82578)
                 goto out;
 
+        /* Do not apply workaround if in PHY loopback bit 14 set */
+        hw->phy.ops.read_phy_reg(hw, PHY_CONTROL, &data);
+        if (data & PHY_CONTROL_LB)
+                goto out;
+
         /* check if link is up and at 1Gbps */
         ret_val = hw->phy.ops.read_phy_reg(hw, BM_CS_STATUS, &data);
         if (ret_val)